From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- arch/microblaze/Makefile | 93 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 arch/microblaze/Makefile (limited to 'arch/microblaze/Makefile') diff --git a/arch/microblaze/Makefile b/arch/microblaze/Makefile new file mode 100644 index 000000000..02e6be9c5 --- /dev/null +++ b/arch/microblaze/Makefile @@ -0,0 +1,93 @@ +# SPDX-License-Identifier: GPL-2.0 +KBUILD_DEFCONFIG := mmu_defconfig + +UTS_SYSNAME = -DUTS_SYSNAME=\"Linux\" + +# What CPU version are we building for, and crack it open +# as major.minor.rev +CPU_VER := $(CONFIG_XILINX_MICROBLAZE0_HW_VER) +CPU_MAJOR := $(word 1, $(subst ., , $(CPU_VER))) +CPU_MINOR := $(word 2, $(subst ., , $(CPU_VER))) +CPU_REV := $(word 3, $(subst ., , $(CPU_VER))) + +export CPU_VER CPU_MAJOR CPU_MINOR CPU_REV + +# Use cpu-related CONFIG_ vars to set compile options. +# The various CONFIG_XILINX cpu features options are integers 0/1/2... +# rather than bools y/n + +# Work out HW multipler support. This is tricky. +# 1. Spartan2 has no HW multipliers. +# 2. MicroBlaze v3.x always uses them, except in Spartan 2 +# 3. All other FPGa/CPU ver combos, we can trust the CONFIG_ settings +ifeq (,$(findstring spartan2,$(CONFIG_XILINX_MICROBLAZE0_FAMILY))) + ifeq ($(CPU_MAJOR),3) + CPUFLAGS-1 += -mno-xl-soft-mul + else + # USE_HW_MUL can be 0, 1, or 2, defining a hierarchy of HW Mul support. + CPUFLAGS-$(subst 1,,$(CONFIG_XILINX_MICROBLAZE0_USE_HW_MUL)) += -mxl-multiply-high + CPUFLAGS-$(CONFIG_XILINX_MICROBLAZE0_USE_HW_MUL) += -mno-xl-soft-mul + endif +endif +CPUFLAGS-$(CONFIG_XILINX_MICROBLAZE0_USE_DIV) += -mno-xl-soft-div +CPUFLAGS-$(CONFIG_XILINX_MICROBLAZE0_USE_BARREL) += -mxl-barrel-shift +CPUFLAGS-$(CONFIG_XILINX_MICROBLAZE0_USE_PCMP_INSTR) += -mxl-pattern-compare + +ifdef CONFIG_CPU_BIG_ENDIAN +KBUILD_CFLAGS += -mbig-endian +KBUILD_AFLAGS += -mbig-endian +KBUILD_LDFLAGS += -EB +else +KBUILD_CFLAGS += -mlittle-endian +KBUILD_AFLAGS += -mlittle-endian +KBUILD_LDFLAGS += -EL +endif + +CPUFLAGS-1 += $(call cc-option,-mcpu=v$(CPU_VER)) + +# r31 holds current when in kernel mode +KBUILD_CFLAGS += -ffixed-r31 $(CPUFLAGS-y) $(CPUFLAGS-1) $(CPUFLAGS-2) + +libs-y += arch/microblaze/lib/ + +boot := arch/microblaze/boot + +# Are we making a simpleImage. target? If so, crack out the boardname +DTB:=$(subst simpleImage.,,$(filter simpleImage.%, $(MAKECMDGOALS))) + +export DTB + +all: linux.bin + +archheaders: + $(Q)$(MAKE) $(build)=arch/microblaze/kernel/syscalls all + +PHONY += linux.bin linux.bin.gz linux.bin.ub +linux.bin.ub linux.bin.gz: linux.bin +linux.bin: vmlinux +linux.bin linux.bin.gz linux.bin.ub: + $(Q)$(MAKE) $(build)=$(boot) $(boot)/$@ + @echo 'Kernel: $(boot)/$@ is ready' ' (#'$(or $(KBUILD_BUILD_VERSION),`cat .version`)')' + +PHONY += simpleImage.$(DTB) +simpleImage.$(DTB): vmlinux + $(Q)$(MAKE) $(build)=$(boot) $(addprefix $(boot)/$@., ub unstrip strip) + @echo 'Kernel: $(boot)/$@ is ready' ' (#'$(or $(KBUILD_BUILD_VERSION),`cat .version`)')' + +define archhelp + echo '* linux.bin - Create raw binary' + echo ' linux.bin.gz - Create compressed raw binary' + echo ' linux.bin.ub - Create U-Boot wrapped raw binary' + echo ' simpleImage.
- Create the following images with
.dtb linked in' + echo ' simpleImage.
: raw image' + echo ' simpleImage.
.ub : raw image with U-Boot header' + echo ' simpleImage.
.unstrip: ELF (identical to vmlinux)' + echo ' simpleImage.
.strip : stripped ELF' + echo ' Targets with
embed a device tree blob inside the image' + echo ' These targets support board with firmware that does not' + echo ' support passing a device tree directly. Replace
with the' + echo ' name of a dts file from the arch/microblaze/boot/dts/ directory' + echo ' (minus the .dts extension).' +endef + +MRPROPER_FILES += $(boot)/simpleImage.* -- cgit v1.3.1